The present invention relates to a method of inspecting a surface of a specimen to inspect for unsatisfactory imperfections in the specimen under test.
Component parts of a machine (e.g., airplane, space shuttle, automobile, etc.) need to be inspected for imperfections that may be unsatisfactory for the designated purpose of the part. For example, a component part of,an airplane may have to be inspected for cracks, scratches and other imperfections. The cracks, scratches, and other imperfections may cause the component part to fail during use or operation of the airplane. Such failure of the component part may be mission critical in that although human life may not be in danger if the component part fails, the airplane may not be able to accomplish the mission at hand. Alternatively, failure of the component part may threaten life if unsatisfactory imperfections, scratches, or cracks are in the component part. Accordingly, certain parts of a device should be tested, especially if they are mission critical parts or safety critical parts.
When inspecting these component parts, it may often be necessary to take microscopic images of surfaces of the component parts. The surface to the inspected may be an exposed flat surface, a hole or have other features. The various configurations of the surface to be inspected may make inspection of the surface difficult. By way of example and not limitation, a hole in the component part may be difficult to inspect via a microscope. The reason is that the surface of the hole may not be able to fit under the microscope. Additionally, the hole may be awkward to inspect via the microscope.
In the prior art, instead of directly inspecting the component part for inspection, a replica of the surface to be inspected of the component part may be made. The replica may be smaller than the component part and conveniently disposed under the microscope. One prior art method of making the replica utilizes an acetate film softened with a solvent. Once the acetate film is softened, the acetate film is placed over the surface to be inspected and allowed to harden. When the acetate film is placed over the surface, the acetate film conforms to the surface of the component part. Any imperfection, scratch or cracks in the surface is molded into the acetate film. Once hardened, the film is removed from the component part and the film is inspected for any imperfections, scratches and cracks. Unfortunately, acetate replicas may be time consuming and require skill and training.
Another method of making replicas utilize a resin. The resin is injected into the hole or onto a surface to be inspected. The imperfections, scratches and cracks in the surface to the inspected are molded into the resin. The resin is then hardened and inspected. The resin may be silicone or a dental casting media. Unfortunately, the casting method may be time consuming because the resin may not cure quickly.
Accordingly, there is a need in the art for an improved method of making a replica to inspect the surface to the inspected for unsatisfactory imperfections.